The present invention generally relates to methods and apparatuses for dissipating heat away from devices generating heat. In addition, the invention relates to methods and other apparatuses for converting heat energy into other forms of energy.
The research and development of liquid metal magneto hydro dynamic energy conversion systems is gaining increasing attention in their various proposed modes, consisting of single-phase or two-phase fluid flow for a wide range of heat sources, e.g., solar energy, waste heat, nuclear energy, etc. Since the thermodynamic “availability,” or energy content, of a solid or fluid increases strongly with absolute temperature, efficient electric power generation from a heat source is usually performed at elevated temperatures, often in the range of 600° C.-800° C. In the categories of high temperature conversion, the systems are generally large, with each generator unit producing megawatts of electric power and occupying a volume of 10 m3 to 100 m3. Alternatively, lower temperature equipment operating between 100° C. and 200° C. have been developed to recover energy from solar-concentrated heated fluids and geothermal sources and waste heat rejected by high temperature conversion systems.
One prior art approach is taught by U.S. Pat. No. 3,878,410, issued to the United States Energy Research and Development Administration, which is directed to a two-phase liquid metal magnetohydrodynamic generator. The '410 patent uses a gas injected into a liquid metal which reduces the density of the liquid metal causing an increased convection flow of the liquid metal within a channel. The liquid metal flows past a heat source where the heat is transferred to the liquid metal. This prior art contains deficiencies, though. For example, as disclosed, the '410 patent requires a pump to circulate the liquid metal through the channel. This additional pump not only adds components to the system and requires maintenance; but also, consumes electrical power. Thus, the '410 patent has to pay an electrical energy penalty for the required pumping. Further, the pump adds vibrational and acoustical interference to the system.
In the marketplace, many products generate heat in the temperature range below 150° C. For example, electrical components, such as integrated circuits including a central processor unit (CPU) for a computer, operating in close proximity in an enclosed electronic apparatus produce heat. To prevent thermal failure of one of the electrical components in the enclosed electronic apparatus this heat needs to be dissipated. These enclosed electronic apparatuses are common and typically include personal computers, laptop computers, display monitors, computer peripherals, television sets, projectors, projection monitors, handheld personal digital assistants (PDAs), cellular phones, facsimile machines, video cassette recorders (VCRs), digital versatile disc (DVD) players, audio systems and similar equipment. Further, slightly larger equipment, such as refrigerators, washers, dryers and other similar appliances also may generate heat in this low temperature range.
Thermal management of the electronic components in the enclosed electronic apparatus is necessary to prevent the enclosed electronic apparatus from failing or to extend the useful life of the enclosed electronic apparatus. For instance, a typical CPU operating in a personal computer may operate at a maximum temperature of 70° C. without experiencing a thermal failure; but due to the heat generated by a typical CPU, however, the temperature often reaches 100° C. and above which could lead to thermal failure.